1. Field of the Invention
The invention is directed to a hydrodynamic coupling device with a hydrodynamic circuit having an impeller wheel and a turbine wheel, a lockup clutch, and a torsional vibration damper with a drive-side transmission element and a driven-side transmission element which is movable relative to the latter, each of the transmission elements having driving means for interacting with circumferentially acting elastic elements.
2. Description of the Related Art
A prior art hydrodynamic coupling device in the form of a torque converter is disclosed in German reference DE 44 33 256 A1, particularly in FIG. 1, with a hydrodynamic circuit having an impeller wheel, a turbine wheel and a stator wheel. This coupling device further includes a lockup clutch having an axially movable piston and a torsional vibration damper. The piston is movable in the direction of a primary flange of the clutch housing by an overpressure in the hydrodynamic circuit, wherein a plate or blade is provided axially between the piston and the primary flange. This type of blade usually has, at both sides, friction facings which engage with friction surfaces at the piston and at the primary flange as soon as the piston loads the friction facing which faces it with axial force. Torque which is present at the clutch housing is then transferred via the blade to the piston.
A radially outer part of the blade engages elastic elements of a damping device of the torsional vibration damper which are constructed as circumferential springs, wherein the elastic elements are supported at the other end at a cover plate which projects inward far enough to enable a fastening to the turbine hub. In this torsional vibration damper, the blade acts as a drive-side transmission element with drive-side driving means for the elastic elements and the cover plate acts as a driven-side transmission element with driven-side driving means.
In the hydrodynamic couplings device according to the above-cited application, the hydrodynamic circuit, torsional vibration damper and piston are arranged axially adjacent to one another, resulting in a relatively large axial installation space requirement. This hydrodynamic coupling device can accordingly be installed, if at all, only with great difficulty, especially in compact automobiles.
In another prior art hydrodynamic coupling device disclosed in the German Offenlegungsschrift 28 10 497, the hydrodynamic device and the piston of a lockup clutch are arranged axially adjacent to one another, but the torsional vibration damper is shifted far inward radially to engage radially inside the turbine wheel in an annular space enclosed by the turbine wheel.
Although axial installation space is saved compared to the hydrodynamic coupling device of reference DE 44 33 256 A1 discussed above, the torsional vibration damper is not completely integrated in the annular space and accordingly still involves a loss of axial installation space. Further, the torsional vibration damper of this prior art device is arranged so far radially inward that only a comparatively small spring path in the circumferential direction is possible.